%0 Journal Article
%T Impact resistance of common spectacle and safety lenses to airgun and rimfire projectiles
%J Journal of the American Association for Pediatric Ophthalmology and Strabismus
%D 2003
%A Rychwalski, Paul J.
%A Packwood, Eric A.
%A Cruz, Oscar A.
%A Holds, John B.
%V 7
%N 4
%P 268-273
%X PURPOSE: To evaluate the penetration resistance of  common spectacle and safety lenses to high-velocity projectiles and to examine  the current recommendations regarding the use of such lenses. METHODS: The  penetration threshold of glass, high-index, and polycarbonate spectacle and  safety lenses was determined by firing BBs, pellets, and 0.22-caliber  projectiles. The mass, diameter, velocity, and energy of each projectile were  measured, and the center thickness, mass, and refractive power of each lens were  recorded. The penetration threshold for each lens type was calculated, and a  comparison of impact resistance was made. RESULTS: The maximum velocity of the  BB was measured at 221 m/s; pellets at 210 m/s; CB.22 rimfire projectiles at 204  m/s; and 0.22 rimfire projectiles at 290 m/s. The BB penetration thresholds were  as follows: glass lenses = 84.0 m/s (2.4 J) and high-index lenses = 107.7 m/s  (4.09 J). Polycarbonate spectacle and safety lenses were not penetrated by BBs  regardless of their velocity; however, these lenses were penetrated by CB.22  rimfire projectiles (89.2 J). Review of the penetrated lenses showed that center  thickness and refractive power was comparable between the various groups of  projectiles. CONCLUSIONS: Polycarbonate offers a vastly superior degree of  penetration resistance compared with other commonly used lens materials. The  current recommendations regarding the use of polycarbonate in prescription and  protective lenses, as endorsed by the American Academy of Ophthalmology and the  American Academy of Pediatrics, must be reevaluated.
%G 
%I Elsevier Publishing
%@ 1091-8531
%U http://dx.doi.org/10.1016/mpa.2003.S1091853103001101